Small Engine Troubleshooting Problems? Ask a Mechanic Now.
Did you check the valves when you had the head off? You may have a valve that is bent and not seating. Do you have good compression?
I see question is still open, did you see my response? Did you check the crankshaft drive gear when you had engine apart? Crankshaft gear has key that could have sheared when the rod broke, this would throw off the internal timing.